Current studies have on the identification of novel antigens expressed in melanoma and renal cancers as well as the characterization of T cells that recognize epitopes of previously described antigens. In a recent study, a novel gene has been identified that encodes an antigen recognized by a T cell clone that was derived from a population of renal cancer reactive TIL. Ongoing studies to extend current immunotherapies to additional patients have also involved the analysis of responses directed against multiple peptide epitopes derived from gp100 and tyrosinase. Additional studies have involved the analysis of responses directed against antigens that are expressed in melanoma as well as a variety of highly prevalent malignancies such as breast and prostate cancer. Fur these studies, sequencing reactions have been carried out using BigDye Terminator Cycle Sequencing Kits and were analyzed on an Applied Biosystems 3100-Avant Genetic Analyzer that represents an integral part of the Surgery Branch DNA Sequencing Core. The FACS Core Facility is currently being utilized for the analysis of T cell populations that are administered to patients as a part of the analysis of ongoing clinical cancer adoptive immunotherapy trials. In addition, the FACS Core is utilized on a daily basis for the analysis of the results of experiments to analyze the results of in vitro experiments to examine factors that influence the phenotype and function of tumor reactive T cells as well as to carry out the separation of cells based upon their expression of cell surface markers. The FACS Core consists of four Becton/Dickinson flow cytometers, a FACSCalibur, two FACSCantos and a FACSARIA cell sorter.